This invention relates to a novel multi-functional lubricant additive which is a dispersant, anti-oxidant and a anti-wear viscosity index (VI) improver additive when employed in a lubricating oil composition.
It is well known to those skilled in the art, that hydrocarbon lubricating oils must be formulated by addition of various additives to improve their properties.
In the case of lubricating oils, typified by those employed in railway, automotive, aircraft, marine etc., service, it is found that they become degraded during use due inter alia to formation of sludge which may be generated by deterioration of the oil or by introduction of undesirable components from other sources including the fuel or the combustion air. In order to maintain and improve the properties of the lubricating oil, various additives have heretofore been provided; and these have been intended to improve the viscosity index, dispersancy, oxidative stability, antiwear properties, etc.
Reduction in cost of lubricating oils and its improved performance can be achieved by using a VI improver which improves not only viscosity index, but is also active as dispersant and antioxidant. Such an additive can be prepared by incorporating dispersant and antioxidant units onto polymer base, typically olefin copolymer (OCP), backbone. The engine test performance of motor oils containing such multifunctional VI improvers is superior to the oils containing commercial monofunctional or dispersant OCP VI improvers and allow a significant reduction in the amount of classical antioxidant and dispersant used in the dispersant/inhibitor packages.